Funny, I would think the opposite. In general, small throat carbs give better
low end torque because of higher air velocity through the carb-but once the
revs go up, the smaller throat restricts the air flow. One of the solutions
for street engines was either a 4 barrel carb with two main throats and a pair
of secondary throats that kicked in at high revs or three two barrels where
the center carb was "slow" running and the two end carbs kicked in at high
revs.
The Stromberg CD150 VV carb tryed to solve this by varying the throat opening
depending on vacuum (thus revs).
Jan Eyerman (more interested in smooth running and torque then ultimate revs)
sosnaenergyconsulting@home.com wrote:
Y'know, Smitty has a Holbay head and we were puzzling over the smaller
intake ports recently. He thought that going from a large carb opening
to a small intake port would increase the velocity of the air/fuel mix.
Wouldn't that contribute to better torque?
I think that somebody else (apologies for not remembering who) wrote
yesterday that the intent of the Holbay head was to make better low-end
torque rather than high-end horsepower.
Regards
David Sosna
56 S4 GT V6
Greg Locke wrote:
>
> I heard that holbay originally delivered the H120 powered rapier (or
> hunter?) with decent sized ports and rootes said... "No way. this is too
> fast, make it slower". The reduction in port size was holbays answer. I
> thought they only reduced the size of the intake manifold runners, and the
> head ports were standard, but I may be wrong here. Would take a lot of work
> to weld up the ports and re bore them.
>
> more information form vague sources.... The original engine did put out
> 120hp, but the port mods reduced it to about 107.
>
> Kindof defeats the purpose of the webers in the first place, but it was
more
> of a sales gimmic anyway, as a result of the london-sydney win.
>
> Greg
>
> ----- Original Message -----
> From: Jarrid Gross <JGross@econolite.com>
> To: Tom Hill <tom.hill@att.net>; Christopher Albers
> <Christopher.Albers@bubbs.biola.edu>
> Cc: <alpines@autox.team.net>
> Sent: Friday, 9 March 2001 09:02
> Subject: RE: RE: More Power from the 1725
>
> > tom wrote,
> >
> > >I am referring to the port diameter at the intake manifold not the valve
> > >size. I think the valves are the same on the standard and Holbay heads.
> >
> > >tom
> >
> > CNA wrote,
> >
> > >Huh? That doesn't seem right. How does the head breath with an intake
> > >only, what, 1.2"? I can't recall the stock size, I seem to recall
> > >about 1.4" for the intake & 1.2" for the exaust.
> >
> >
> >
> > This is correct, the ports on the holbay are about 1.25.
> >
> > The valves are 1.30 and 1.52, the same and SV alpines.
> >
> >
> > Jarrid Gross
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